CA1148687A - Process for the continuous mass polymerization of polyblends - Google Patents
Process for the continuous mass polymerization of polyblendsInfo
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- CA1148687A CA1148687A CA000377592A CA377592A CA1148687A CA 1148687 A CA1148687 A CA 1148687A CA 000377592 A CA000377592 A CA 000377592A CA 377592 A CA377592 A CA 377592A CA 1148687 A CA1148687 A CA 1148687A
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- Prior art keywords
- rubber
- monomer
- polymer
- styrene
- polybutadiene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
- C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Graft Or Block Polymers (AREA)
Abstract
Case No. 08-12-0423 A PROCESS FOR THE CONTINUOUS MASS
POLYMERIZATION OF POLYBLENDS
ABSTRACT OF THE INVENTION
The present invention relates to an improved pro-cess for the continuous mass polymerization of solutions comprising alkenyl aromatic monomers having about 1 to 10% by weight of a polybutadiene rubber dissolved therein, the steps comprising, (A) continuously charging said solu-tion to a first reaction zone operating at about 20 to 45% conversion forming a first partially polymerized mix-ture, (B) continuously charging said first mixture to a second reaction zone operating at about 50-85% conver-sion forming a second partially polymerized mixture, and finally, (C) separating the residual monomer from said second mixture providing a polyblend of a matrix phase of said monomers having polybutadiene rubber particles grafted with said monomers dispersed therein, the improve-ment comprising: charging a monomer-polybutadiene solution in step (A) having in addition about 1 to 10% by weight of a diene block copolymer and about 1 to 20% by weight of a polymer of said monomers dissolved in said solution followed by carrying out steps (B) and (C) to provide a polyblend of a polymer of said monomers having dispersed therein rubber particles grafted with said monomers, said rubber particles containing said polybutadiene and diene block copolymer rubbers and forming a gel phase of said rubber particles containing grafted and occluded poly-mers of said monomers in an amount of about 0.5 to 5 parts per part of total rubber.
POLYMERIZATION OF POLYBLENDS
ABSTRACT OF THE INVENTION
The present invention relates to an improved pro-cess for the continuous mass polymerization of solutions comprising alkenyl aromatic monomers having about 1 to 10% by weight of a polybutadiene rubber dissolved therein, the steps comprising, (A) continuously charging said solu-tion to a first reaction zone operating at about 20 to 45% conversion forming a first partially polymerized mix-ture, (B) continuously charging said first mixture to a second reaction zone operating at about 50-85% conver-sion forming a second partially polymerized mixture, and finally, (C) separating the residual monomer from said second mixture providing a polyblend of a matrix phase of said monomers having polybutadiene rubber particles grafted with said monomers dispersed therein, the improve-ment comprising: charging a monomer-polybutadiene solution in step (A) having in addition about 1 to 10% by weight of a diene block copolymer and about 1 to 20% by weight of a polymer of said monomers dissolved in said solution followed by carrying out steps (B) and (C) to provide a polyblend of a polymer of said monomers having dispersed therein rubber particles grafted with said monomers, said rubber particles containing said polybutadiene and diene block copolymer rubbers and forming a gel phase of said rubber particles containing grafted and occluded poly-mers of said monomers in an amount of about 0.5 to 5 parts per part of total rubber.
Description
6~
A PROCESS FOR THE CONTINUOVS MASS
POLYMERIZATION OF POLYBLENDS
.
BACKGROUND OE THE INVENTION
It is known to polymerize solutions comprising alkenyl aromatic monomers having a diene rubber dissolved therein to form polyblends having a matrix phase of polymers of-said mcnomers having dispersed therein particles of said diene rubber grafted with said monomers.
Mass and mass/suspension processes have been used to prepare such polyblends. U. S. Patent 3,903,202 is one such suitable process for the continuous mass polymerization of such polyblends~
The morphology of the rubber particles dispersed in the polyblend is critical to the final properties of the poly- :
blend. Generally, the larger the size of said rubber par-ticles, the greater the toughness and the smaller ~he size, the higher the gloss. Hence, the size of the rubber par-ticles must be controlled to insure the control of the properties of the polybIend. U. S. Patent 3,903,202 dis-closes that agitation during the early phases of polymeriza-tion disperses the dissolved rubber as particles and that higher rates of agitation generally decreases the size of said particles with lower rates of agitation producing larger particles.
Beyond the rubber particle si7e morphology and its con-tribution to tol-ghness, it has been found that the internal morphology of the particle is also important to the rubber efficiency in toughening rubber reinforced polyblends.
It has been found that the greater the amount of .
t~
A PROCESS FOR THE CONTINUOVS MASS
POLYMERIZATION OF POLYBLENDS
.
BACKGROUND OE THE INVENTION
It is known to polymerize solutions comprising alkenyl aromatic monomers having a diene rubber dissolved therein to form polyblends having a matrix phase of polymers of-said mcnomers having dispersed therein particles of said diene rubber grafted with said monomers.
Mass and mass/suspension processes have been used to prepare such polyblends. U. S. Patent 3,903,202 is one such suitable process for the continuous mass polymerization of such polyblends~
The morphology of the rubber particles dispersed in the polyblend is critical to the final properties of the poly- :
blend. Generally, the larger the size of said rubber par-ticles, the greater the toughness and the smaller ~he size, the higher the gloss. Hence, the size of the rubber par-ticles must be controlled to insure the control of the properties of the polybIend. U. S. Patent 3,903,202 dis-closes that agitation during the early phases of polymeriza-tion disperses the dissolved rubber as particles and that higher rates of agitation generally decreases the size of said particles with lower rates of agitation producing larger particles.
Beyond the rubber particle si7e morphology and its con-tribution to tol-ghness, it has been found that the internal morphology of the particle is also important to the rubber efficiency in toughening rubber reinforced polyblends.
It has been found that the greater the amount of .
t~
- 2 - C-08~12-0423 gra~ted and occluded polymer produced in the rub~er particle the greater ils effective volume fraction becomes per con-centration of rubber, hence, the greater i-ts toughening efficiency. The total rubber, including graft and occlu-sions, is commonly called the gel content or insoluble por-tion of the polyblend when dissolved in a 601vent for the matrix polymer phase.
The prior art continuous mass polymerization processes have attempted to increase the gel phase of polyblends by running the first reaction zone at less than about 15% con-version to ocelude more monomer in the rubber phase as it is dispersed in the first reaction zones as disclosed in U. S. P. 3,658,946. Such processes require a plurality of reaction zones, i.e., t~ree to four, since the first stage reaction zone only converts about 2 to 10% of the monomers and additional stages are required to finish the polymer-ization with heat and temperature control. Capital and energy costs become prohibitive in today's technology.
U.S.P. 3,660,535 discloses a continuous mass process for rubber monomer solutions wherein the solutions are moved through stratified or plug flow reaction zones starting at zero conversion and ending at essentially 99% conversion through a plurality of staged reactors.
This process differs from that of U.S.P. 3,658,9~6 in that it is plug flow gradual polymerization having a gradual inversion of the rubber phase as the solution is polymerized from 0 to about 15 to 20% conversion. The process of U.S.P.
The prior art continuous mass polymerization processes have attempted to increase the gel phase of polyblends by running the first reaction zone at less than about 15% con-version to ocelude more monomer in the rubber phase as it is dispersed in the first reaction zones as disclosed in U. S. P. 3,658,946. Such processes require a plurality of reaction zones, i.e., t~ree to four, since the first stage reaction zone only converts about 2 to 10% of the monomers and additional stages are required to finish the polymer-ization with heat and temperature control. Capital and energy costs become prohibitive in today's technology.
U.S.P. 3,660,535 discloses a continuous mass process for rubber monomer solutions wherein the solutions are moved through stratified or plug flow reaction zones starting at zero conversion and ending at essentially 99% conversion through a plurality of staged reactors.
This process differs from that of U.S.P. 3,658,9~6 in that it is plug flow gradual polymerization having a gradual inversion of the rubber phase as the solution is polymerized from 0 to about 15 to 20% conversion. The process of U.S.P.
3,658,946 operates with steady-state polymerization reactors wherein the monomer-rubber solution enters a first reactor operating at less than 16% conversion and precipitates and disperses the rubber phase instantaneously with large amounts of occluded monomer in the rubber particles and then feeds the solution to subsequent reactors each operating at steady state conversion in stepwise fashion.
The present process differs from U.S.P. 3,658,946 pro-cess in that the first reaction zone is operating at an efficient 20 to 45% conversion and the monomer-rubber-poly-mer stream enters and disperses as a rubber particle having ~;~ monomer and polymer occluded in the particle. It has been discovered that ~is monomer solution can be fed ~o high conversion efficient first reaction zones because the poly-mer in the reaction will not partiticn occluded monomers or polymer from the particles because the polymer in the par-ticles holds the monomer in the particles having as high anaffinity for the monomer as the polymer already formed in the reaction zone. In addition the block copolymers have the ability to hold the monomers and polymer in the rubber phase having a polybutadiene end compatible with the rubber phase and a polystyrene end compatible with the monomer and polymers to hold them in the rubber phase particles.
The present invention then provides a continuous pro-cess for preparing polyblends having increased rubber effi-ciency without using a large number of staged reactors.
Efficient polymerization is provided in only two efficient polymerization zones running at high conversions and poly rates yet providing the polyblend produced with high rubber gel fractions.
It is the objective of the present invention to provide a process that will produce a rubber phase in polyblends and have an increased rubber volume fraction as a gel wherein larger amounts of grafted and occluded polymers are present in amounts of 1 to 5 parts per part of rubber.
It is the objective of the present invention to provide a continuous process wherein rubber-polymer-monomer solu-tions are polymerized in steady-state, flow-through, poly-merization zones such that volume fraction of the rubber phase is increased beyond the contribution of the rubber moiety charged.
SUMMARY OF THE INVENTION
The present invention relates to an impro~ed method for the mass polymerizing of a solution comprising an alkenyl aromatic monomer having a polybutadiene rubber dissolved therein, the steps comprising:
~. continuously charging said monomer solution having 1 to 10% of a polybutadiene rubber dissolved therein to a first reaction zone operating at steady state polymerization of about 20 to 45% of said monomers to a .
' . ~
The present process differs from U.S.P. 3,658,946 pro-cess in that the first reaction zone is operating at an efficient 20 to 45% conversion and the monomer-rubber-poly-mer stream enters and disperses as a rubber particle having ~;~ monomer and polymer occluded in the particle. It has been discovered that ~is monomer solution can be fed ~o high conversion efficient first reaction zones because the poly-mer in the reaction will not partiticn occluded monomers or polymer from the particles because the polymer in the par-ticles holds the monomer in the particles having as high anaffinity for the monomer as the polymer already formed in the reaction zone. In addition the block copolymers have the ability to hold the monomers and polymer in the rubber phase having a polybutadiene end compatible with the rubber phase and a polystyrene end compatible with the monomer and polymers to hold them in the rubber phase particles.
The present invention then provides a continuous pro-cess for preparing polyblends having increased rubber effi-ciency without using a large number of staged reactors.
Efficient polymerization is provided in only two efficient polymerization zones running at high conversions and poly rates yet providing the polyblend produced with high rubber gel fractions.
It is the objective of the present invention to provide a process that will produce a rubber phase in polyblends and have an increased rubber volume fraction as a gel wherein larger amounts of grafted and occluded polymers are present in amounts of 1 to 5 parts per part of rubber.
It is the objective of the present invention to provide a continuous process wherein rubber-polymer-monomer solu-tions are polymerized in steady-state, flow-through, poly-merization zones such that volume fraction of the rubber phase is increased beyond the contribution of the rubber moiety charged.
SUMMARY OF THE INVENTION
The present invention relates to an impro~ed method for the mass polymerizing of a solution comprising an alkenyl aromatic monomer having a polybutadiene rubber dissolved therein, the steps comprising:
~. continuously charging said monomer solution having 1 to 10% of a polybutadiene rubber dissolved therein to a first reaction zone operating at steady state polymerization of about 20 to 45% of said monomers to a .
' . ~
- 4 - C-08-12-0423 first ?ar-tially polymerized mixture, said mixture being said monomer having polymers of said monomer and polybuta-diene rubber particles grafted with said monomer dispersed in said monomers, . continuously charging said partially polymerized mixture to a second reaction zone operating at a final polymerization of about 50 to 85% of said monomer form-ing a second partially polymerized mix-ture, C. continuously separating the residual monomer from said se~ond mixture providing a matrix phase polymer of said monomer having said grafted rubber partîcles dis-persed therein, said improvement compris-ing: charging a monomer-polybutadiene solu-tion in step (A) having in addition about 1 to 10% of a diene block copolymer and ~0 about 1 to 20% by weight of a polymer of said monomer dissolved in said solution followed by carrying out steps (B) and (C) to f~rm a polyblend of said matrix phase polymer having rubber partioles grafted with said monomers dispersed therein, said rubber particles containing rubbers consist-ing of polybutadiene and diene block copoly-mer, said rubber particles being a gel frac-tion in said polyblend containing grafted and occluded polymers of said monomers in amount of about 0.5 to 5 parts per part of total rubber.
PREFERRED EMBODIMENTS
. . ~
Exemplary of the monomers that can be employed in the present process are styrene; alpha-alkyl monovinylidene monoaromatic compounds, e.g. alpha-methylstyrene, alpha-ethylstyrene, alpha-methylvinyltoluene, etc.; ring-substi-tuted alkyl styrenes, e.g. vinyl toluene, o-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, etc.; ring-substituted ., ,:, . . - : -, '7
PREFERRED EMBODIMENTS
. . ~
Exemplary of the monomers that can be employed in the present process are styrene; alpha-alkyl monovinylidene monoaromatic compounds, e.g. alpha-methylstyrene, alpha-ethylstyrene, alpha-methylvinyltoluene, etc.; ring-substi-tuted alkyl styrenes, e.g. vinyl toluene, o-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, etc.; ring-substituted ., ,:, . . - : -, '7
- 5 - C-08-12-0~23 halostyrenes, e.g. o-~hlorostyrene, p-chlorostyrene, o-bromostyrene, 2,4-dichlorostyrene, etc.; ring-alkyl, ring-halo-substituted styrenes, e.g. 2-chloro-4-methylstyrene, 2,6-dichloro-4-methyls-tyrene, etc. If so desired, mixtures of such monovinylidene aromatic monomers may be employed.
The alkenyl aromatic monomer can be used in combination with comonomers such as alkenyl nitrile; e.g., acrylonitrile methacrylonitrile, etc., or acrylates such as acrylic acid, methacrylic acid, methyl methacrylate, etc.
The styrene-acrylonitrile monomers having, l to 15% by weight a diene rubber dissolved therein, can be continuously mass polymerized to polyblends known as ABS. Such poly-blends can contain styrene and acrylonitrile type monomers in weight ratios of about 90:10 to 50:50 respectively, 15 preferably 80:20 to 70:30 by weight.
In addition to the monomers to be polymeri~ed, the formulation can contain catalyst where required and other desirable components such as stabilizers, molecular weight regulators, etc.
The polymerization may be initiated by thermal mono-meric free radicals, however, any free radical generating catalyst may be used in the practice of this invention in-cluding actinic irradiation. Conventional monomer-soluble peroxy and perazo catalysts may be used. Exemplary cata-lysts are di-tert-butyl peroxide, benzoyl peroxide, lauroyl peroxide, oleyl peroxide, toluyl peroxide, di-tert-butyl diperphthalate, tert-butyl peracetate, tert-butyl perben-zoate, dicumyl peroxide, tert-butyl peroxide isopropyl car-bonate, 2,5-dimethyl-2,5-dimethyl-2,5-di-~tert-butylperoxy) 30 nexane, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane-3 or hexyne-3, tert-butyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide, cyclopentane hydroperoxide, pin-ane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, etc., and mixtures thereof.
The catalyst is generally included within the range of 0.001 to 3.0% by weight and preferably on the order of 0.005 to 1.0% by weight of the polymerizable material, de-pending primarily upon the monomer present.
As is well known, it is often desirable to incorpor-~, :
The alkenyl aromatic monomer can be used in combination with comonomers such as alkenyl nitrile; e.g., acrylonitrile methacrylonitrile, etc., or acrylates such as acrylic acid, methacrylic acid, methyl methacrylate, etc.
The styrene-acrylonitrile monomers having, l to 15% by weight a diene rubber dissolved therein, can be continuously mass polymerized to polyblends known as ABS. Such poly-blends can contain styrene and acrylonitrile type monomers in weight ratios of about 90:10 to 50:50 respectively, 15 preferably 80:20 to 70:30 by weight.
In addition to the monomers to be polymeri~ed, the formulation can contain catalyst where required and other desirable components such as stabilizers, molecular weight regulators, etc.
The polymerization may be initiated by thermal mono-meric free radicals, however, any free radical generating catalyst may be used in the practice of this invention in-cluding actinic irradiation. Conventional monomer-soluble peroxy and perazo catalysts may be used. Exemplary cata-lysts are di-tert-butyl peroxide, benzoyl peroxide, lauroyl peroxide, oleyl peroxide, toluyl peroxide, di-tert-butyl diperphthalate, tert-butyl peracetate, tert-butyl perben-zoate, dicumyl peroxide, tert-butyl peroxide isopropyl car-bonate, 2,5-dimethyl-2,5-dimethyl-2,5-di-~tert-butylperoxy) 30 nexane, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane-3 or hexyne-3, tert-butyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide, cyclopentane hydroperoxide, pin-ane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, etc., and mixtures thereof.
The catalyst is generally included within the range of 0.001 to 3.0% by weight and preferably on the order of 0.005 to 1.0% by weight of the polymerizable material, de-pending primarily upon the monomer present.
As is well known, it is often desirable to incorpor-~, :
- 6 - ~-08-12-0423 ate molecular weight regulators such as mercaptans, halides and terpenes in relatively small percentages by weight, on the order of 0.001 to 1.0% by weight of the polymeriæable material. From 2 to 20% diluents such as ethylbenzene, ethyltoluene~ ethylxylene, diethylbenzene or benzene may be added to the monomer composition to control viscosities at high conversions and also provide some molecular weight regulation. In addition, it may be desirable to include relatively small amounts of antioxidants or stabilizers such as the conventional alkylated phenols. Alternatively, these may be added during or after polymerization. The formula-tion may also contain other additives such as plasticizers, lubricants, colorants and non-reactive preformed polymeric materials which are suitable or dispersible therein.
THE RUBBER SUBSTRATE
Exemplary of the various rubbers onto which the polymerizable monomer formulation can be grafted during polymerization in the presence thereof to produce the graft copolymers are diene rubbers~ natural rubbers, ethylene-propylene terpolymer rubbers, acrylate rubbers, polyiso-prene rubbers and mixtures thereof, as well as interpoly-mers thereof with each other or other copolymerizable mono-mers.
The preferred substrates, however, are diene rubbers (including mixtures of diene rubbers), i.e., any rubbery polymer (a rubbery polymer having a second order transition temperature not higher than 0 centigrade, preferably not higher than -20 centigrade, as determined by ASTM Test D-7~6-52T) of one or more of the conjugated, 1,3 dienes, e.g. butadiene, isoprene, 2-chloro-1,3 butadiene, l chloro-1,3-butadiene, piperylene, etc. Such rubbers include co-polymers and block copolymers of conjugated 1,3-dienes with up to an e~ual amount by weight of one or more copolymer-izable monoethylenically unsaturated monomers, such as monovinylidene aromatic hydrocarbons (e.g. styrene; an aralkylstyrene, such as the o-, m- and p-methylstyrenes, 2,4-dimethylstyrene, the arethylstyrenes, p-tert-butylsty-rene, etc.; an alphamethylstyrene, alphaethylstyrene, alpha-methyl-p-methyl styrene, etc.; vinyl naphthalene, etc.);
-;
:
THE RUBBER SUBSTRATE
Exemplary of the various rubbers onto which the polymerizable monomer formulation can be grafted during polymerization in the presence thereof to produce the graft copolymers are diene rubbers~ natural rubbers, ethylene-propylene terpolymer rubbers, acrylate rubbers, polyiso-prene rubbers and mixtures thereof, as well as interpoly-mers thereof with each other or other copolymerizable mono-mers.
The preferred substrates, however, are diene rubbers (including mixtures of diene rubbers), i.e., any rubbery polymer (a rubbery polymer having a second order transition temperature not higher than 0 centigrade, preferably not higher than -20 centigrade, as determined by ASTM Test D-7~6-52T) of one or more of the conjugated, 1,3 dienes, e.g. butadiene, isoprene, 2-chloro-1,3 butadiene, l chloro-1,3-butadiene, piperylene, etc. Such rubbers include co-polymers and block copolymers of conjugated 1,3-dienes with up to an e~ual amount by weight of one or more copolymer-izable monoethylenically unsaturated monomers, such as monovinylidene aromatic hydrocarbons (e.g. styrene; an aralkylstyrene, such as the o-, m- and p-methylstyrenes, 2,4-dimethylstyrene, the arethylstyrenes, p-tert-butylsty-rene, etc.; an alphamethylstyrene, alphaethylstyrene, alpha-methyl-p-methyl styrene, etc.; vinyl naphthalene, etc.);
-;
:
- 7 - C-08-12-0423 arhalo monovinylidene aromatic hydrocarbons (e.g. the o-, m- and p-chlorostyrene, 2,4-dibromostyrene, 2-methyl-4-chlorostyrene, etc.); acrylonitrile; methacrylonitrile;
alkyl acrylates te.g. methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), the corresponding alkyl meth-acrylates; acrylamides (e.g. acrylamide, methacrylamide, N-butylacrylamide, etc.); unsaturated ketones (e.g. vinyl methyl ketone, methyl isopropenyl ketone, etc.); alpha-olefins (e.g. ethylene, propylene, etc.); pyridines; vinyl esters (e.g. vinyl acetate, vinyl stearate, etc.); vinyl and vinylidene halides (e.g. the vinyl and vinylidene chlorides and bromides, etc.); and the like.
Although the rubber may contain up to about 2.0% of a crosslinking agent, based on the weight of the rubber-form-ing monomer or monomers, crosslinking may present problemsin dissolving the rubber in the monomers for the graft polymerization reaction. In addition, excessive crosslink-ing can result in loss of the rubber characteristics.
A preferred group of rubbers are the stereospecific polybutadiene rubbers formed by the polymerization of 1,3-butadiene. These rubbers have a cis-isomer content of about 30-98% and a trans-isomer content of about 70-2~ and gener-ally contain at least about 85% of polybutadiene formed by 1,4 addition with no more than about 15% by 1,2 addition.
Mooney viscosities of the rubber (ML-4, 212F.) can range from about 20 to 70 with a second order transition tempera-ture of from about -50 to -105C. as determined by ASTM
Test D-746-52T.
GRAFTED RUBBER PHASE
A monomer composition comprising at least one mono-alkenyl aromatic monomer having about 1-10% by weight of a diene rubber, 1-10% of a diene block copolymer and 1-20% of a polymer dissolved therein is charged continuously as a monomer-rubber solution to the initial reaction zone. The 35 monomer is polymerized at temperatures of about 110-145C.
in the first zone converting about 20-45% by weight of the monomer to a alkenyl aromatic polymer, already described, as a first polymer. At least a portion of the first polymer polymerized is grafted as polymer molecules to the diene B~7
alkyl acrylates te.g. methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), the corresponding alkyl meth-acrylates; acrylamides (e.g. acrylamide, methacrylamide, N-butylacrylamide, etc.); unsaturated ketones (e.g. vinyl methyl ketone, methyl isopropenyl ketone, etc.); alpha-olefins (e.g. ethylene, propylene, etc.); pyridines; vinyl esters (e.g. vinyl acetate, vinyl stearate, etc.); vinyl and vinylidene halides (e.g. the vinyl and vinylidene chlorides and bromides, etc.); and the like.
Although the rubber may contain up to about 2.0% of a crosslinking agent, based on the weight of the rubber-form-ing monomer or monomers, crosslinking may present problemsin dissolving the rubber in the monomers for the graft polymerization reaction. In addition, excessive crosslink-ing can result in loss of the rubber characteristics.
A preferred group of rubbers are the stereospecific polybutadiene rubbers formed by the polymerization of 1,3-butadiene. These rubbers have a cis-isomer content of about 30-98% and a trans-isomer content of about 70-2~ and gener-ally contain at least about 85% of polybutadiene formed by 1,4 addition with no more than about 15% by 1,2 addition.
Mooney viscosities of the rubber (ML-4, 212F.) can range from about 20 to 70 with a second order transition tempera-ture of from about -50 to -105C. as determined by ASTM
Test D-746-52T.
GRAFTED RUBBER PHASE
A monomer composition comprising at least one mono-alkenyl aromatic monomer having about 1-10% by weight of a diene rubber, 1-10% of a diene block copolymer and 1-20% of a polymer dissolved therein is charged continuously as a monomer-rubber solution to the initial reaction zone. The 35 monomer is polymerized at temperatures of about 110-145C.
in the first zone converting about 20-45% by weight of the monomer to a alkenyl aromatic polymer, already described, as a first polymer. At least a portion of the first polymer polymerized is grafted as polymer molecules to the diene B~7
- 8 - C-08-12-0423 rubber as superstrate.
The diene block copolymers are those having greater than 50% by weight of a conjugated diene monomer, as dis-closed supra, as a diene block copolymerized with a alkenyl aromatic monomeric polymer as a block segment of the poly-mer. The diene block copolymers then are preferably, poly-butadiene-polystyrene or polystyrene-polybutadiene-polysty-rene in copolymeric structure and have the following molecu-lar structure:
(.. -BBBBBBBBBB)X - (SSSSSS-~)y wherein B represents butadiene and S represents styrene, X
represents from 55 to 90 preferably 60 to 80 and y repre-sents 10-45 preferably 20 to 40% by weight of each monomer in the block copolymer. The diene block copolymers are lS available commercially and have a Mooney viscosity (M~ +4 at 100C.) of about 35 to 55 or an intrinsic viscos-ity in toluene of about 1 to 5. The diene block copolymers are present in the monomer-rubber solution in amounts of about 1 to 10% by weight in combination with about 1 to 10%
by weight of polybutadiene and 1 to 20% by weight of poly-mers of the cited monomers, such as, alkenylaromatic or mixtures of alkenyl aromatic and alkenyl nitrile monomers.
Although the amount of polymeric superstrate grafted onto the rubber substrate may vary from as little as 10.0 parts by weight to 100.0 parts of substrate to as much as 250.0 per 100.0 parts and even higher, the preferred graft copolymers will generally have a superstrate to substrate ratio of about 20 to 200:100 and most desirably about 30 to 150:100. With graft ratios about 30 to 150:100; a highly desirable degree of improvement in various properties gen-erally is obtained.
The remainder of the first polymer formed is dissolved in said monomer composition as polymerized forming a mono-mer-polymer solution. The monomer-polymer solution or phase is incompatible with the monomer-rubber solution or phase and phase separation is observed by the well known Dobry effect. As the polymer concentration of -the monomer poly-, .
- g - C-08-12-0423 ner-phase increases and has a volu~e slightly larger than the monomer-rubber phase, the monomer-rubber phase disperses as rubber-monomer particles aided by the shearing agitation of the stirred first reaction 7one.
The agitation must be significant and of high enough shear to disperse and size the rubber particles uni.formly throughout the monomer-polymer phase. The intensity of the stirring will vary with the size and geometry of the initial reactor, however, simple experimentation with a given stirred reactor will establish the sufficient amount of stirring needed to insure the homogeneous dispersion of the rubber particles throughout the monomer-polymer phase. The particle size of the rubber can be varied from a weight average particle diameter of from about O.S to 10 microns preferably from 0.5 to 5 microns to provide a balance be-tween the impact strength and the gloss of the rubber rein-forced polyblend. Higher stirring rates and shearing agi-tation can lower the size of the dispersed rubber particle, hence, must be controlled to provide sufficient stirring -to size the particles to the predetermined size needed and in-sure homogeneous dispersion.
At steady state polymerization, in the initial poly-meriæation zone, the continuously charged monomer composi- -tion disperses rapidly under stirring, forming the rubber-monomer-polymer particles which on complete polymerization form discrete rubber particles. The conversion of monomers to polymers in the first reaction zone is controlled be-tween 20-45% and must have a weight percent level that pro-vides a polymer content in excess of the rubber content of the monomer composition to insure the dispersion of the monomer-rubber phase to a rubber-monomer particle phase having a predetermined size and being dispersed uniformly throughout the monomer-polymer phase.
The rubber particle becomes grafted with a first poly-mer in the first reaction zone which aids its dispersionand stabilizes the morphology of the particle. During the dispersion of the rubber-monomer-polymer particles, monomer-polymer phase is occluded within the particle. The total amount of occluded monomer-polymer phase and grafted poly-- . : ~ . :
mer present in the particles can be ~rom about 1 to 5 grams for each gram of said diene rubber and diene block copoly-mer.
The dispersed rubber phase increases the toughness of the polymeric polyblend as measured by its Izod impact strength by Test ASTM D-256-56. It has been found that the impact strength of polyblends increase with the weight per-cent rubber dispersed in the polyblend in the range of 2 to 15% as used in the present invention. The impact strength is also determined by the size of the dispersed rubber par-ticles, with the larger particles providing higher impact strength in the range of 0.5 to 10 microns measured as a weight average particle size diameter with a photosedimen~
tometer by the published procedure of Graves, M. J. et.al., "Size Analysis of Subsieve Powders Using a Centrifugal Photosedimentometer", British Chemical Engineering 9:742-744 (1964). A Model 3000 Particle Size Analyzer from Martin Sweets Co., 3131 West Market Street, Louisville, Kentucky was used.
The weight average diameter of the rubber particles also afects gloss with smaller particles giving high gloss and the larger particles giving low gloss to the fabricated polyblend article such as a molding or sheet product. One must balance impact strength and gloss requirements in se- --lecting an optimum rubber particle size. The range of 0.5 to 10 microns can be used with the range of 0.5 to 5 mi-crons being preferred and 0.8 to 3 microns being most pre-ferred for optimum impact strength and gloss.
Processwise, in the initial reactor, one must (1) form and disperse the rubber particle and (2) graft and stabil-ize the rubber particle maintaining its size and morphology or structure. The amount of occluded monomer-polymer phase described above is held at a predetermined level described above by steady state polymerization wherein the monomer is converted to polymer, at least a portion of which, grafts to the rubber stabilizing the rubber particle. It has been îound that the higher the amount of occlusion stabilized within the rubber particle the more efficiently the rubber phase is used in toughening the polyblend. The rubber par-:.
::
- ll - C-08-12-04~3 ticle acts much as a pure rubber particle if the occlusions are controlled at the amount described above during their stabilization in the initial reaction zone and throughout the total polymerization process. The rubber particle is also grafted externally stabilizing its structure as to size and its dispersibility in the monomer-polymer phase.
The initial reactor forms a first mixture or partially polymerized solution of a monomer-polymer phase having the rubber phase described dispersed therein. The first mixture can be charged to a staged isobaric reaction zone as a second zone and described herein. The first mixture is polymerized by progressive multistage substantial linear flow polymerizations with the conversion of polymer advanc-ing from about 20-45% conversion in the first stage to 50 to 85% conversion in the final stage of the staged isobaric stirred reaction zone as a second zone. This provides a gradual progressive increase of polymer in the monomer-polymer phase. This has been found to be important in main-taining the morphology or structure of the dispersed rubber-monomer particles.
It has been found unexpectedly that in the initial re-action zone as the rubber particle is formed, that the rubber-monomer particle has a monomer content that corres~-ponds to the monomer content of the monomer-polymer phase.
The rubber-monomer particle will stabilize at this level as the monomer polymerizes inside the rubber particle and grafted polymer is formed on the outside. Hence, it has been found that the lower the level o* conversion or polymer in the monomer-polymer phase of the initial reactor the higher the amount of monomer found in the rubber-monomer particles formed as the rubber solution is charged and dis-persed in the monomer-polymer phase. Conversely, if the conversion is high in the initial stage less monomer is oc-cluded in the rubber phase particle on dispersion.
The present invention overcomes this problem by adding block copolymer rubbers and polymers of the monomers used in the monomer solution to the monomer solution having the polybutadiene rubber dissolved therein. It has been dis~-covered that the first reaction zone can be run at a high . . .
8S~37 steady-state polymerization conversion of about 20-~5~ to obtain efficient polymerization rates yet retain increased amounts of polymer and monomer in the rubber phase particles as they are formed and dispersed in the partially polymer-ized mixture being formed continuously in the first back-mixed, non linear reaction zone.
It has been found that the diene block copolymer rub-bers are compatible in the monomer-polybutadiene rubber solution and in turn compatibil:ize the polymer and monomers associated with the rubber phase such that the rubber phase will disperse essentially instantaneously in the partially polymerized mixture as monomer-rubber globules due to the interfacial activity of the diene block copolymers. Hence, the diene block copolymers are acting as a dispersing aid lS as to rubber phase and is also inhibiting any partitioning of the occluded monomers and polymers from the rubber phase into the partially polymerized mixture, hence, giving a rub-ber phase of larger volume as dispersed increasing rubber toughening efficiency and improving polyblend proper-ties as a product of the present process and adding to the utility of the process, i.e., a low cost, highly efficient process that overcomes the problems of the prior art continuous processes.
As described earlier, the first mixture can be polymer-ized in the staged linear flow second zone and the percentby weight of polymer being formed is progressively higher with each stage having a slightly higher polymer content.
The staged linear progressive polymerization was found not only to control the polymerization of the monomer giving desirable polymers but was found unexpectedly to preserve the integrity of the rubber particles. Although not com-pletely understood, as the rubber particle becomes grafted and the monomer-polymer phase forms in the occluded monomer of the rubber particle, the monomer is not readily extracted from the rubber particle by the monomer-polymer phase as the polymer content increases gradually in the monomer-polymer phase during polymerizing in the staged reactor. It is thought that since the polymerization in the multistaged linear reaction zone is so gradual that polymer is being ' -., : ; :.: :
`:
: . ~ -:. .
q ~ 7 formed in both the rubber particle and the monomer-polymer phase at about the same rate, hence, the total polymer con-tent of -the occluded monomer-polymer phase of the rubber particle is about the same as polymer content of the mono-mer-polymer phase and monomer is not extracted, hence, the weight percent of occlusion is stabilized and remains sub-stantially constant after formation in the initial reactor.
It has been found possible to analyze the amount of total occluded polymer phase and grafted polymers. The final polymerized polyblend product (1 gram) are dispersed in a 50/50 acetone/methyl ethyl ketone solvent (10 ml.) which dissolves the polymer phase matrix leaving the rubber phase dispersed. The rubber phase is separated from the dispersion by centrifuge as a gel and dri.ed in a vacuum oven at 50C. for 12 hours and weighed as a dry gel.
% Dry gel Weight of dry gel x 100 in Polyblend ~ Weight of polyblend % Graft and ) % dry gel - % rubber Occlusions ) = Percent rubber' x 100 in Rubber Parts~ by weight of graft polymer ) % dry ael - % rubber and occluded poly- ) = Percent rubber mer per unit weight ) of rubber ~' Percent rubber determined by infra-red spectrochemical analysis of the dry gel ~:; The present invention preferably has present about 0.5 to 5 grams of occluded and grafted polymer per gram of diene rubber particle.
The swelling index of the rubber graft particles is determined by taking the dry gel above and dispersing it in toluene for 12 hours. The gel is separated by centrifuge and the supernatant toluene drained free. The wet gel is weighed and then dried in vacuum oven for 12 hours at 50C.
and weighed.
, .
.
- 14 - C-0~-12-0423 Swelling Index = weight of wet gel weight of dry gel As described earlier the amount of occlusions and graft polymer present in the rubber particle is present in the amount of about 0.5 to 5 part for each part of diene rubber.
The percent dry gel measured above then is the per~ent gel in the polymerized polyblend and represents the dispersed rubber phase havin~ polymeric occlusions and polymeric graft. The percent gel varies with the percent rubber charged in the monomer composition and the total amount of graft an~ occluded polymer present in the rubber phase.
The swelling index of the rubber as determinéd above is important to the final properties of the polyblend. A
low swelling index indicates that the rubber has been cross-linked by the monomer as it polymerizes to a polymer phase in the rubber-monomer particle during steps tA3 and (B).
Generally, the conversion of monomer to polymer in the oc-clusion follows the rate of conversion of monomer to poly-mer in the monomer-polymer phase being carried out in steps tA) and (B). The rubber particles can become crosslinked by heating the second mixture to from about 200 to 250C.
during step (C) for sufficient time to crosslink the rubber particles such that they have a swelling index of from about 7 to 20 preferably from about 8 to 16.
Preferably, the combine~d polymer of the matrix phase of the polyblends produced by this invention have a disper-sion index (Mw/Mn), wherein Mw is a weight average molecu-lar weight and Mn is a number average molecular weight, ranging from about 2.0 to 4.0 preferably 2.2 to 3.5. The dispersion index is well known to those skilled in the art and represents the molecular weight distribution with the lower values having narrow molecular weight distribution and higher values having broader molecular weight distribu-tion. The weight average molecular weight of the combined polymer of the matrix phase preferably ran~es from 150,000 to 300,000.
, .- ,': ' ~ .
, : , .
': ' .
SECOND REACTION ZONE POLYMERIZATION
The second reaction zone polymerization can be carried out in a staged isobaric stirred reaction zone maintaining conditions so as to polymerize said firs-t mixture by pro-gressive multistage substantially linear flow polymerizationall said stages operating with shearing agitation and common evaporation vapor phase cooling ~mder isobaric conditions in said second reaction zone, providing each said stage with steady state polymerization at controlled temperature and inter~acial liquid contact stage to stage establishing a hydraulic pressure gradient from the first stage downstream to the final stage causing substantially linear flow through said second zone, all said stages operating at predetermined conversion levels producing a composite polymer as a second polymer in said second reaction zone having a predetermined molecular weight distribution and average molecular weight maintaining the structural integrity of said dispersed`rub-ber particle~ said second zone producing a second mixture having a total polymer content being determined by said multistage steady state polymerization and evaporation of said monomers.
The reactor operates under controlled isobaric condi-tions. Eor the range of temperatures normally of interest for alkenyl aromatic monomers, e.g. styrene polymerization (130-180C.), the operating pressure will range from 7 to 28 psia. The styrene reaction is e~othermic and cooling is provided primarily by vaporization of a part of the monomer from the rea~ting mass. Further cooling can be provided by a jacket. Cooling by the condensed recycle monomer feeding into either the first or second reaction zone is also pro-vided. The mass is in a boiling condition and temperature is determined by the natural relationship between vapor pressure and boiling point. This relationship is also a runction of the relative amounts of polymer, monomer and other substances (e.g. dissolved rubber~ solvents and addi-tives). Since, as material progresses through this reactor the amount of polymer continuously increases and the amount of monomer correspon~ngly decreases via polymerization and ; monomer content further decreases due to vaporization loss, .
, .
- 16 - C-08-12-04~3 the temperature progressively increases from inlet to outlet stages.
To accommodate the natural swell of the boiling mass and to provide space for vapor disengagement, the reactor is usually run at a fillage of abou~ 10 to 90% preferably 40 to 50% of its volume.
Vapor passes out of the reactor to an external conden-ser where it is condensed and may also be sub-cooled. This condensate may then be handled in several ways, for ex-ample:
1. If the reactor used in this invention is preceded by another reactor in a multi-reactor train, the condensate may be re-turned to a preceding reactor.
2. The condensate may be returned to the inlet compartment of the reactor used in this invention, wherein it is re-heated by condensation of a ~raction of the previously evolved vaporS and mixed other incoming free materials.
In a multi-compartment staged reactor, each stage is well mixed and the reaction mass is substantially homogen-eous within itself. The discs which separate the stages discourage backflow of material between compartments. The clearance between disc and shell does permit some backflow and also permits the necessary forwarding of material through the compartments from reactor inlet to outlet giving substantially linear flow.
In a compartmented staged reactor as here described, the first stage has a relatively low conversion level, since it is being continuously fed by monomer and low conversion prepolymerized syrup. However, the rate of conversion in this stage is relatively high because of the high concentra-tion of monomer.
In each succeeding stage, the conversion level is higher than in the preceding one, which tends to lower the rate of conversion. Offsetting this effect, however, are the facts that the temperature is higher and that monomer is being vaporized out of the mass. Thus, the total conversion .
' .
' - 17 - C-08-~.2-0423 to polymer ob~;ained per unit fillage volume of the staged reactor is higher than that which could be obtained in a single stage reactor producing an equal final conversion level at equal tempera'cure.
Clearance between rotating disc compartment baffles and cylindrical wall may be from 1 to 10% of shell radius, the larger values being appropriate to the high conversion end of the reactor w~ere viscosity is at maximum. Stage to stage forward flow ~f the polymerizing first mixture is through this clearance and vapor from the polymerizing first mixture also counterflowsthrough the clearance~ above the surface level of the mass.
If the alkenyl monomer is used in combination with an alkenyl nitrile monomer, operations are essentially the same except for controlling the styrene-acrylonitrile composition of the monomers during polymerization. The styrene type monomer adds to the copolymer at a faster rate than the acrylonitrile monomer, hence, the acrylonitrile monomer is generally charged at higher weight percentages in the charged monomer formulation to insure a desired weight per-cent in the polymerized copolymer. The two monomers form an azeotrope at about 75% styrene and 25~ acrylonitrile so that no shift in monomer or polymer composition occurs during polymerization, hence, generally the azeotropic monomer mix-ture is used in the continuous mass polymerizing o~ ABSpolyblends from monomer-rubber solutions.
The polyalkenyl aromatic monomer polymer or copolymer to be dissolved in the monomer-rubber solutions to be îed in step (A) is preferably a polystyrene type polymer or styrene-acrylonitrile type copolymer having a weight average molecu-lar weight of about 20,000 to 300,000 preferably about 150,000 to 250,000. The matrix polymer or copolymer can have a weight average molecular weight of about 150,000 to 300,000.
The amount of polymer or copolymer to be added is de-pendent on the particle size desired in the polyblend. Gen-erally, the more polymer present, the larger is the rubber particle size as dispersed. The amount to be used is also based on the amount of rubber dissolved in the monomer to be .
. - . , ', , - ' . .~ ~ .
-fed in step (A~. The amount of polymer or copolymer present in the monomer-rubber solution is about 1 to 20% by weight based on the monomer solution.
The following examples are set forth to more clearly illustrate the principles and practice of the present in-vention. They are intended to be illustrative and not limiting as to the scope of the invention.
~XAMPLE 1 ~ CONTROL
A monomer composition consisting of 5 parts by weight of stereospecific polybutadiene rubber in 95 parts by weight of styrene monomer is prepared by agitating the mix-ture at 40C. for ô hours. The rubber used contains ap-proximately 35% cis-1,4 structure; approximately 55% trans-1,4 structure and approximately 10% vinyl-1,2 structure having a Mooney viscosity of the rubbe~ (ML-4, 212F.) ~
55. To the above monomer composition is added 0.5 parts of white mineral oil, 0.1 part by weight of octadecyl 3-~3', 5'-di-tertbutyl-4-hydroxyphenyl) propionate and 40 parts by weight of recycled styrene monomer. This monomer composi-tion is fed continuously at approximately 145 lbs./hr. to a100-gal. anchor agitated initial reactor operated at ap-proximately 50% fillage and 124C. under 5 psig. nitrogen pressure. The agitator is approximately 31 inches wide and turns at 65 rpm. A first mixture containing approximately 20% polystyrene i~ pumped from the above reactor at a con-tinuous rate such as to maintain essentially constant fill-age therein and flows to the inlet of the second reactor, a staged isobaric stirred reactor. The second reactor has approximately a 50 gal. capacity and operates at about ~0%
fillage.
The reactor is about 53 inches long. The agitator con-sists of a horizontal shaft on which are fixed a series of paddles about 2 inches wide alternating at right angles to one another in a manner similar to that sho~n in U. S.
Patent 3,903,202. Along the shaft and rotating with it are four circular discs with an average radial wall clearance of about three-eighth inch rotating at lS rpm. These discs are positioned to divide the reactor into five stages of approximately equal volume. The pressure in this reactor .
.
' . .
is maintained at approximately 20 psia.
The second mi~ture in the final stage is maintained at about 166C. and contains about 62% polystyrene. Styrene vapor evaporated from the second reactor is condensed and the condensate is returned to the first compartment. The second mixture is pumped continuously from the final stage at a rate to maintain essentially constant fillage in the second reactor and is delivered to the inlet of the devola-tilizer preheater. The second mixture exits from the pre heater at approximately 240C. and enters a devolatilizer chamber maintained at 50 torr. Second mixture volatile vapors exiting the devolatilizer chamber are condensed and recycled to the first reactor preheater feed system. Ap-proximately 3 lbs.thr. of the condensed devolatilized vapors are withdrawn as purge. The devolatilized melt is fed from the devolatilizer chamber to an extruder which forms it into a plurality of strands which are then cooled and cut into pellets. The combined polymer has a molecular weight of about 210,000 and a dispersion index about 3.1.
Typical Properties Izod Impact 1/2" x 1/2" bar 73F. (ft.lb./in . 1. O
Tensile strength at yield (lb.in.) 3800 Tensile strength at fail (lb./in.) 3750 Tensile elongation at fail (%) 62 Swelling index 9 Parts graft and occlusions/rubber 1.43:1 Rubber particle size (microns) 1.5 -Example 1 was repeated using varying amounts of poly-butadiene, diene block copolymers, polymer and monomers as the solution charged to the process to illustrate the gel fraction of the polyblends can be increased by novel feed streams to baclc-mixed, steady state polymerization reaction zone operating at about 20 to ~5% conversion. Formulations "
shown in par-ts and test data are tabula-ted in Table I.
`
~ ` : - , .
TABLE I
Block Izod PBD ( CopolyT~e~ Parts ( Monomer(4) Impac-t %
Ex. Rubber 1) Rubber Monomers 3) Polymer Strength Gel 5 1 5 0 95(S) 0 1.0 12.5 2 4 1 91(S) 4 1.37 13.3 3 3 2 91(S) 4 1.51 15.1 4 7 G 93(S) 0 1.62 18.2 2 87(S) 6 1.83 20.1 10 6 4 3 87(S) 6 1.85 21.6 7 10 0 90(S) 0 1.85 24.0 8 5 5 85(S) 5 2.51 29.2
The diene block copolymers are those having greater than 50% by weight of a conjugated diene monomer, as dis-closed supra, as a diene block copolymerized with a alkenyl aromatic monomeric polymer as a block segment of the poly-mer. The diene block copolymers then are preferably, poly-butadiene-polystyrene or polystyrene-polybutadiene-polysty-rene in copolymeric structure and have the following molecu-lar structure:
(.. -BBBBBBBBBB)X - (SSSSSS-~)y wherein B represents butadiene and S represents styrene, X
represents from 55 to 90 preferably 60 to 80 and y repre-sents 10-45 preferably 20 to 40% by weight of each monomer in the block copolymer. The diene block copolymers are lS available commercially and have a Mooney viscosity (M~ +4 at 100C.) of about 35 to 55 or an intrinsic viscos-ity in toluene of about 1 to 5. The diene block copolymers are present in the monomer-rubber solution in amounts of about 1 to 10% by weight in combination with about 1 to 10%
by weight of polybutadiene and 1 to 20% by weight of poly-mers of the cited monomers, such as, alkenylaromatic or mixtures of alkenyl aromatic and alkenyl nitrile monomers.
Although the amount of polymeric superstrate grafted onto the rubber substrate may vary from as little as 10.0 parts by weight to 100.0 parts of substrate to as much as 250.0 per 100.0 parts and even higher, the preferred graft copolymers will generally have a superstrate to substrate ratio of about 20 to 200:100 and most desirably about 30 to 150:100. With graft ratios about 30 to 150:100; a highly desirable degree of improvement in various properties gen-erally is obtained.
The remainder of the first polymer formed is dissolved in said monomer composition as polymerized forming a mono-mer-polymer solution. The monomer-polymer solution or phase is incompatible with the monomer-rubber solution or phase and phase separation is observed by the well known Dobry effect. As the polymer concentration of -the monomer poly-, .
- g - C-08-12-0423 ner-phase increases and has a volu~e slightly larger than the monomer-rubber phase, the monomer-rubber phase disperses as rubber-monomer particles aided by the shearing agitation of the stirred first reaction 7one.
The agitation must be significant and of high enough shear to disperse and size the rubber particles uni.formly throughout the monomer-polymer phase. The intensity of the stirring will vary with the size and geometry of the initial reactor, however, simple experimentation with a given stirred reactor will establish the sufficient amount of stirring needed to insure the homogeneous dispersion of the rubber particles throughout the monomer-polymer phase. The particle size of the rubber can be varied from a weight average particle diameter of from about O.S to 10 microns preferably from 0.5 to 5 microns to provide a balance be-tween the impact strength and the gloss of the rubber rein-forced polyblend. Higher stirring rates and shearing agi-tation can lower the size of the dispersed rubber particle, hence, must be controlled to provide sufficient stirring -to size the particles to the predetermined size needed and in-sure homogeneous dispersion.
At steady state polymerization, in the initial poly-meriæation zone, the continuously charged monomer composi- -tion disperses rapidly under stirring, forming the rubber-monomer-polymer particles which on complete polymerization form discrete rubber particles. The conversion of monomers to polymers in the first reaction zone is controlled be-tween 20-45% and must have a weight percent level that pro-vides a polymer content in excess of the rubber content of the monomer composition to insure the dispersion of the monomer-rubber phase to a rubber-monomer particle phase having a predetermined size and being dispersed uniformly throughout the monomer-polymer phase.
The rubber particle becomes grafted with a first poly-mer in the first reaction zone which aids its dispersionand stabilizes the morphology of the particle. During the dispersion of the rubber-monomer-polymer particles, monomer-polymer phase is occluded within the particle. The total amount of occluded monomer-polymer phase and grafted poly-- . : ~ . :
mer present in the particles can be ~rom about 1 to 5 grams for each gram of said diene rubber and diene block copoly-mer.
The dispersed rubber phase increases the toughness of the polymeric polyblend as measured by its Izod impact strength by Test ASTM D-256-56. It has been found that the impact strength of polyblends increase with the weight per-cent rubber dispersed in the polyblend in the range of 2 to 15% as used in the present invention. The impact strength is also determined by the size of the dispersed rubber par-ticles, with the larger particles providing higher impact strength in the range of 0.5 to 10 microns measured as a weight average particle size diameter with a photosedimen~
tometer by the published procedure of Graves, M. J. et.al., "Size Analysis of Subsieve Powders Using a Centrifugal Photosedimentometer", British Chemical Engineering 9:742-744 (1964). A Model 3000 Particle Size Analyzer from Martin Sweets Co., 3131 West Market Street, Louisville, Kentucky was used.
The weight average diameter of the rubber particles also afects gloss with smaller particles giving high gloss and the larger particles giving low gloss to the fabricated polyblend article such as a molding or sheet product. One must balance impact strength and gloss requirements in se- --lecting an optimum rubber particle size. The range of 0.5 to 10 microns can be used with the range of 0.5 to 5 mi-crons being preferred and 0.8 to 3 microns being most pre-ferred for optimum impact strength and gloss.
Processwise, in the initial reactor, one must (1) form and disperse the rubber particle and (2) graft and stabil-ize the rubber particle maintaining its size and morphology or structure. The amount of occluded monomer-polymer phase described above is held at a predetermined level described above by steady state polymerization wherein the monomer is converted to polymer, at least a portion of which, grafts to the rubber stabilizing the rubber particle. It has been îound that the higher the amount of occlusion stabilized within the rubber particle the more efficiently the rubber phase is used in toughening the polyblend. The rubber par-:.
::
- ll - C-08-12-04~3 ticle acts much as a pure rubber particle if the occlusions are controlled at the amount described above during their stabilization in the initial reaction zone and throughout the total polymerization process. The rubber particle is also grafted externally stabilizing its structure as to size and its dispersibility in the monomer-polymer phase.
The initial reactor forms a first mixture or partially polymerized solution of a monomer-polymer phase having the rubber phase described dispersed therein. The first mixture can be charged to a staged isobaric reaction zone as a second zone and described herein. The first mixture is polymerized by progressive multistage substantial linear flow polymerizations with the conversion of polymer advanc-ing from about 20-45% conversion in the first stage to 50 to 85% conversion in the final stage of the staged isobaric stirred reaction zone as a second zone. This provides a gradual progressive increase of polymer in the monomer-polymer phase. This has been found to be important in main-taining the morphology or structure of the dispersed rubber-monomer particles.
It has been found unexpectedly that in the initial re-action zone as the rubber particle is formed, that the rubber-monomer particle has a monomer content that corres~-ponds to the monomer content of the monomer-polymer phase.
The rubber-monomer particle will stabilize at this level as the monomer polymerizes inside the rubber particle and grafted polymer is formed on the outside. Hence, it has been found that the lower the level o* conversion or polymer in the monomer-polymer phase of the initial reactor the higher the amount of monomer found in the rubber-monomer particles formed as the rubber solution is charged and dis-persed in the monomer-polymer phase. Conversely, if the conversion is high in the initial stage less monomer is oc-cluded in the rubber phase particle on dispersion.
The present invention overcomes this problem by adding block copolymer rubbers and polymers of the monomers used in the monomer solution to the monomer solution having the polybutadiene rubber dissolved therein. It has been dis~-covered that the first reaction zone can be run at a high . . .
8S~37 steady-state polymerization conversion of about 20-~5~ to obtain efficient polymerization rates yet retain increased amounts of polymer and monomer in the rubber phase particles as they are formed and dispersed in the partially polymer-ized mixture being formed continuously in the first back-mixed, non linear reaction zone.
It has been found that the diene block copolymer rub-bers are compatible in the monomer-polybutadiene rubber solution and in turn compatibil:ize the polymer and monomers associated with the rubber phase such that the rubber phase will disperse essentially instantaneously in the partially polymerized mixture as monomer-rubber globules due to the interfacial activity of the diene block copolymers. Hence, the diene block copolymers are acting as a dispersing aid lS as to rubber phase and is also inhibiting any partitioning of the occluded monomers and polymers from the rubber phase into the partially polymerized mixture, hence, giving a rub-ber phase of larger volume as dispersed increasing rubber toughening efficiency and improving polyblend proper-ties as a product of the present process and adding to the utility of the process, i.e., a low cost, highly efficient process that overcomes the problems of the prior art continuous processes.
As described earlier, the first mixture can be polymer-ized in the staged linear flow second zone and the percentby weight of polymer being formed is progressively higher with each stage having a slightly higher polymer content.
The staged linear progressive polymerization was found not only to control the polymerization of the monomer giving desirable polymers but was found unexpectedly to preserve the integrity of the rubber particles. Although not com-pletely understood, as the rubber particle becomes grafted and the monomer-polymer phase forms in the occluded monomer of the rubber particle, the monomer is not readily extracted from the rubber particle by the monomer-polymer phase as the polymer content increases gradually in the monomer-polymer phase during polymerizing in the staged reactor. It is thought that since the polymerization in the multistaged linear reaction zone is so gradual that polymer is being ' -., : ; :.: :
`:
: . ~ -:. .
q ~ 7 formed in both the rubber particle and the monomer-polymer phase at about the same rate, hence, the total polymer con-tent of -the occluded monomer-polymer phase of the rubber particle is about the same as polymer content of the mono-mer-polymer phase and monomer is not extracted, hence, the weight percent of occlusion is stabilized and remains sub-stantially constant after formation in the initial reactor.
It has been found possible to analyze the amount of total occluded polymer phase and grafted polymers. The final polymerized polyblend product (1 gram) are dispersed in a 50/50 acetone/methyl ethyl ketone solvent (10 ml.) which dissolves the polymer phase matrix leaving the rubber phase dispersed. The rubber phase is separated from the dispersion by centrifuge as a gel and dri.ed in a vacuum oven at 50C. for 12 hours and weighed as a dry gel.
% Dry gel Weight of dry gel x 100 in Polyblend ~ Weight of polyblend % Graft and ) % dry gel - % rubber Occlusions ) = Percent rubber' x 100 in Rubber Parts~ by weight of graft polymer ) % dry ael - % rubber and occluded poly- ) = Percent rubber mer per unit weight ) of rubber ~' Percent rubber determined by infra-red spectrochemical analysis of the dry gel ~:; The present invention preferably has present about 0.5 to 5 grams of occluded and grafted polymer per gram of diene rubber particle.
The swelling index of the rubber graft particles is determined by taking the dry gel above and dispersing it in toluene for 12 hours. The gel is separated by centrifuge and the supernatant toluene drained free. The wet gel is weighed and then dried in vacuum oven for 12 hours at 50C.
and weighed.
, .
.
- 14 - C-0~-12-0423 Swelling Index = weight of wet gel weight of dry gel As described earlier the amount of occlusions and graft polymer present in the rubber particle is present in the amount of about 0.5 to 5 part for each part of diene rubber.
The percent dry gel measured above then is the per~ent gel in the polymerized polyblend and represents the dispersed rubber phase havin~ polymeric occlusions and polymeric graft. The percent gel varies with the percent rubber charged in the monomer composition and the total amount of graft an~ occluded polymer present in the rubber phase.
The swelling index of the rubber as determinéd above is important to the final properties of the polyblend. A
low swelling index indicates that the rubber has been cross-linked by the monomer as it polymerizes to a polymer phase in the rubber-monomer particle during steps tA3 and (B).
Generally, the conversion of monomer to polymer in the oc-clusion follows the rate of conversion of monomer to poly-mer in the monomer-polymer phase being carried out in steps tA) and (B). The rubber particles can become crosslinked by heating the second mixture to from about 200 to 250C.
during step (C) for sufficient time to crosslink the rubber particles such that they have a swelling index of from about 7 to 20 preferably from about 8 to 16.
Preferably, the combine~d polymer of the matrix phase of the polyblends produced by this invention have a disper-sion index (Mw/Mn), wherein Mw is a weight average molecu-lar weight and Mn is a number average molecular weight, ranging from about 2.0 to 4.0 preferably 2.2 to 3.5. The dispersion index is well known to those skilled in the art and represents the molecular weight distribution with the lower values having narrow molecular weight distribution and higher values having broader molecular weight distribu-tion. The weight average molecular weight of the combined polymer of the matrix phase preferably ran~es from 150,000 to 300,000.
, .- ,': ' ~ .
, : , .
': ' .
SECOND REACTION ZONE POLYMERIZATION
The second reaction zone polymerization can be carried out in a staged isobaric stirred reaction zone maintaining conditions so as to polymerize said firs-t mixture by pro-gressive multistage substantially linear flow polymerizationall said stages operating with shearing agitation and common evaporation vapor phase cooling ~mder isobaric conditions in said second reaction zone, providing each said stage with steady state polymerization at controlled temperature and inter~acial liquid contact stage to stage establishing a hydraulic pressure gradient from the first stage downstream to the final stage causing substantially linear flow through said second zone, all said stages operating at predetermined conversion levels producing a composite polymer as a second polymer in said second reaction zone having a predetermined molecular weight distribution and average molecular weight maintaining the structural integrity of said dispersed`rub-ber particle~ said second zone producing a second mixture having a total polymer content being determined by said multistage steady state polymerization and evaporation of said monomers.
The reactor operates under controlled isobaric condi-tions. Eor the range of temperatures normally of interest for alkenyl aromatic monomers, e.g. styrene polymerization (130-180C.), the operating pressure will range from 7 to 28 psia. The styrene reaction is e~othermic and cooling is provided primarily by vaporization of a part of the monomer from the rea~ting mass. Further cooling can be provided by a jacket. Cooling by the condensed recycle monomer feeding into either the first or second reaction zone is also pro-vided. The mass is in a boiling condition and temperature is determined by the natural relationship between vapor pressure and boiling point. This relationship is also a runction of the relative amounts of polymer, monomer and other substances (e.g. dissolved rubber~ solvents and addi-tives). Since, as material progresses through this reactor the amount of polymer continuously increases and the amount of monomer correspon~ngly decreases via polymerization and ; monomer content further decreases due to vaporization loss, .
, .
- 16 - C-08-12-04~3 the temperature progressively increases from inlet to outlet stages.
To accommodate the natural swell of the boiling mass and to provide space for vapor disengagement, the reactor is usually run at a fillage of abou~ 10 to 90% preferably 40 to 50% of its volume.
Vapor passes out of the reactor to an external conden-ser where it is condensed and may also be sub-cooled. This condensate may then be handled in several ways, for ex-ample:
1. If the reactor used in this invention is preceded by another reactor in a multi-reactor train, the condensate may be re-turned to a preceding reactor.
2. The condensate may be returned to the inlet compartment of the reactor used in this invention, wherein it is re-heated by condensation of a ~raction of the previously evolved vaporS and mixed other incoming free materials.
In a multi-compartment staged reactor, each stage is well mixed and the reaction mass is substantially homogen-eous within itself. The discs which separate the stages discourage backflow of material between compartments. The clearance between disc and shell does permit some backflow and also permits the necessary forwarding of material through the compartments from reactor inlet to outlet giving substantially linear flow.
In a compartmented staged reactor as here described, the first stage has a relatively low conversion level, since it is being continuously fed by monomer and low conversion prepolymerized syrup. However, the rate of conversion in this stage is relatively high because of the high concentra-tion of monomer.
In each succeeding stage, the conversion level is higher than in the preceding one, which tends to lower the rate of conversion. Offsetting this effect, however, are the facts that the temperature is higher and that monomer is being vaporized out of the mass. Thus, the total conversion .
' .
' - 17 - C-08-~.2-0423 to polymer ob~;ained per unit fillage volume of the staged reactor is higher than that which could be obtained in a single stage reactor producing an equal final conversion level at equal tempera'cure.
Clearance between rotating disc compartment baffles and cylindrical wall may be from 1 to 10% of shell radius, the larger values being appropriate to the high conversion end of the reactor w~ere viscosity is at maximum. Stage to stage forward flow ~f the polymerizing first mixture is through this clearance and vapor from the polymerizing first mixture also counterflowsthrough the clearance~ above the surface level of the mass.
If the alkenyl monomer is used in combination with an alkenyl nitrile monomer, operations are essentially the same except for controlling the styrene-acrylonitrile composition of the monomers during polymerization. The styrene type monomer adds to the copolymer at a faster rate than the acrylonitrile monomer, hence, the acrylonitrile monomer is generally charged at higher weight percentages in the charged monomer formulation to insure a desired weight per-cent in the polymerized copolymer. The two monomers form an azeotrope at about 75% styrene and 25~ acrylonitrile so that no shift in monomer or polymer composition occurs during polymerization, hence, generally the azeotropic monomer mix-ture is used in the continuous mass polymerizing o~ ABSpolyblends from monomer-rubber solutions.
The polyalkenyl aromatic monomer polymer or copolymer to be dissolved in the monomer-rubber solutions to be îed in step (A) is preferably a polystyrene type polymer or styrene-acrylonitrile type copolymer having a weight average molecu-lar weight of about 20,000 to 300,000 preferably about 150,000 to 250,000. The matrix polymer or copolymer can have a weight average molecular weight of about 150,000 to 300,000.
The amount of polymer or copolymer to be added is de-pendent on the particle size desired in the polyblend. Gen-erally, the more polymer present, the larger is the rubber particle size as dispersed. The amount to be used is also based on the amount of rubber dissolved in the monomer to be .
. - . , ', , - ' . .~ ~ .
-fed in step (A~. The amount of polymer or copolymer present in the monomer-rubber solution is about 1 to 20% by weight based on the monomer solution.
The following examples are set forth to more clearly illustrate the principles and practice of the present in-vention. They are intended to be illustrative and not limiting as to the scope of the invention.
~XAMPLE 1 ~ CONTROL
A monomer composition consisting of 5 parts by weight of stereospecific polybutadiene rubber in 95 parts by weight of styrene monomer is prepared by agitating the mix-ture at 40C. for ô hours. The rubber used contains ap-proximately 35% cis-1,4 structure; approximately 55% trans-1,4 structure and approximately 10% vinyl-1,2 structure having a Mooney viscosity of the rubbe~ (ML-4, 212F.) ~
55. To the above monomer composition is added 0.5 parts of white mineral oil, 0.1 part by weight of octadecyl 3-~3', 5'-di-tertbutyl-4-hydroxyphenyl) propionate and 40 parts by weight of recycled styrene monomer. This monomer composi-tion is fed continuously at approximately 145 lbs./hr. to a100-gal. anchor agitated initial reactor operated at ap-proximately 50% fillage and 124C. under 5 psig. nitrogen pressure. The agitator is approximately 31 inches wide and turns at 65 rpm. A first mixture containing approximately 20% polystyrene i~ pumped from the above reactor at a con-tinuous rate such as to maintain essentially constant fill-age therein and flows to the inlet of the second reactor, a staged isobaric stirred reactor. The second reactor has approximately a 50 gal. capacity and operates at about ~0%
fillage.
The reactor is about 53 inches long. The agitator con-sists of a horizontal shaft on which are fixed a series of paddles about 2 inches wide alternating at right angles to one another in a manner similar to that sho~n in U. S.
Patent 3,903,202. Along the shaft and rotating with it are four circular discs with an average radial wall clearance of about three-eighth inch rotating at lS rpm. These discs are positioned to divide the reactor into five stages of approximately equal volume. The pressure in this reactor .
.
' . .
is maintained at approximately 20 psia.
The second mi~ture in the final stage is maintained at about 166C. and contains about 62% polystyrene. Styrene vapor evaporated from the second reactor is condensed and the condensate is returned to the first compartment. The second mixture is pumped continuously from the final stage at a rate to maintain essentially constant fillage in the second reactor and is delivered to the inlet of the devola-tilizer preheater. The second mixture exits from the pre heater at approximately 240C. and enters a devolatilizer chamber maintained at 50 torr. Second mixture volatile vapors exiting the devolatilizer chamber are condensed and recycled to the first reactor preheater feed system. Ap-proximately 3 lbs.thr. of the condensed devolatilized vapors are withdrawn as purge. The devolatilized melt is fed from the devolatilizer chamber to an extruder which forms it into a plurality of strands which are then cooled and cut into pellets. The combined polymer has a molecular weight of about 210,000 and a dispersion index about 3.1.
Typical Properties Izod Impact 1/2" x 1/2" bar 73F. (ft.lb./in . 1. O
Tensile strength at yield (lb.in.) 3800 Tensile strength at fail (lb./in.) 3750 Tensile elongation at fail (%) 62 Swelling index 9 Parts graft and occlusions/rubber 1.43:1 Rubber particle size (microns) 1.5 -Example 1 was repeated using varying amounts of poly-butadiene, diene block copolymers, polymer and monomers as the solution charged to the process to illustrate the gel fraction of the polyblends can be increased by novel feed streams to baclc-mixed, steady state polymerization reaction zone operating at about 20 to ~5% conversion. Formulations "
shown in par-ts and test data are tabula-ted in Table I.
`
~ ` : - , .
TABLE I
Block Izod PBD ( CopolyT~e~ Parts ( Monomer(4) Impac-t %
Ex. Rubber 1) Rubber Monomers 3) Polymer Strength Gel 5 1 5 0 95(S) 0 1.0 12.5 2 4 1 91(S) 4 1.37 13.3 3 3 2 91(S) 4 1.51 15.1 4 7 G 93(S) 0 1.62 18.2 2 87(S) 6 1.83 20.1 10 6 4 3 87(S) 6 1.85 21.6 7 10 0 90(S) 0 1.85 24.0 8 5 5 85(S) 5 2.51 29.2
9 5 5 90(S) 0 2.33 26.0 81(S) 9 2.73 31.6 1511 5 0 95(S/AN) 0 2.30 13.2 12 4 1 91(SJAN) 4 2.61 15.5 13 3 2 91(S/AN) 4 2.75 17.4 14 10 0 90(S/AN) 0 4.10 22.6 90(S/AN) 0 4.34 25.6 2016 5 5 81(S/AN) 9 6.23 33.0 17 10 10 62(S/AN)15 8.50 52.0 18 10 10 62(S) 15 4.3 49.1 (1) Polybutadiene Rubber (2) Block copolymer rubber-butadiene-styrene (70J30) (3) Monomer (S) is styrene S/AN is styrene-acrylonitrile (4) Monomer polymer is polymer of monomers used in (3), i.e., (A) polymeri~es to polystyrene and S~AN to poly SAN
(5) Gel is the total amount of insoluble rubber phase including graft and occluded polymer as described supra.
.~
~ ' -, ~
It is e~ident from the data that diene block copolymers added to the monomer feed stream 2rovide higher levels of graft and occlusions as gels, however, the greatest gain is found by including polymers of the monomers in the feed stream to insure the placing of polymeric occlusions in the rubber particle to increase rubber toughening efficiency.
.
: '
(5) Gel is the total amount of insoluble rubber phase including graft and occluded polymer as described supra.
.~
~ ' -, ~
It is e~ident from the data that diene block copolymers added to the monomer feed stream 2rovide higher levels of graft and occlusions as gels, however, the greatest gain is found by including polymers of the monomers in the feed stream to insure the placing of polymeric occlusions in the rubber particle to increase rubber toughening efficiency.
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: '
Claims (22)
1. In an improved method for the mass polymerizing of a solution comprising an alkenyl aromatic monomer having a polybutadiene rubber dissolved therein, the steps com-prising:
A. continuously charging said monomer solution having 1 to 10% of a poly-butadiene rubber dissolved therein to a first reaction zone operating at steady state polymerization of about 20 to 45% of said monomers to a first partially polymerized mix-ture, said mixture being said mono-mer having polymers of said monomer and polybutadiene rubber particles grafted with said monomer dispersed in said monomers, B. continuously charging said partially polymerized mixture to a second re-action zone operating at a final polymerization of about 50 to 85% of said monomer forming a second par-tially polymerized mixture, C. continuously separating the residual monomer from said second mixture pro-viding a matrix phase polymer of said monomer having said grafted rubber particles dispersed therein, said im-provement comprising: charging a mono-mer-polybutadiene solution in step (A) having in addition about 1 to 10% of a diene block copolymer and about 1 to 20% by weight of a polymer of said monomer dissolved in said solution followed by carrying out steps (B) and (C) to form a polyblend of said matrix phase polymer having rubber particles grafted with said monomers dispersed therein, said rubber particles con-taining rubbers consisting of poly-butadiene and diene block copolymer, said rubber particles being a gel fraction in said polyblend containing grafted and occluded polymers of said monomers in amount of about 0.5 to 5 parts per part of total rubber.
A. continuously charging said monomer solution having 1 to 10% of a poly-butadiene rubber dissolved therein to a first reaction zone operating at steady state polymerization of about 20 to 45% of said monomers to a first partially polymerized mix-ture, said mixture being said mono-mer having polymers of said monomer and polybutadiene rubber particles grafted with said monomer dispersed in said monomers, B. continuously charging said partially polymerized mixture to a second re-action zone operating at a final polymerization of about 50 to 85% of said monomer forming a second par-tially polymerized mixture, C. continuously separating the residual monomer from said second mixture pro-viding a matrix phase polymer of said monomer having said grafted rubber particles dispersed therein, said im-provement comprising: charging a mono-mer-polybutadiene solution in step (A) having in addition about 1 to 10% of a diene block copolymer and about 1 to 20% by weight of a polymer of said monomer dissolved in said solution followed by carrying out steps (B) and (C) to form a polyblend of said matrix phase polymer having rubber particles grafted with said monomers dispersed therein, said rubber particles con-taining rubbers consisting of poly-butadiene and diene block copolymer, said rubber particles being a gel fraction in said polyblend containing grafted and occluded polymers of said monomers in amount of about 0.5 to 5 parts per part of total rubber.
2. A process of Claim 1 wherein said alkenyl aro-matic monomer is selected from the group consisting of styrene, a-methyl styrene, chlorostyrene, dichlorostyrene, bromostyrene or dibromostyrene and mixtures thereof.
3. A process of Claim 1 wherein said diene rubber is selected from the group consisting of polybutadiene, polyisoprene, poly-2-chlorobutadiene, poly-1-chlorobuta-diene, copolymers and block copolymers of butadiene-sty-rene, butadiene-chloroprene, chloroprene-styrene, chloro-prene-isoprene, 2-chlorobutadiene-1-chlorobutadiene and mixtures thereof.
4. A process of Claim 1 wherein said diene rubber is polybutadiene.
5. A process of Claim 4 wherein said polybutadiene rubber has a cis isomer content of about 30 to 98% and a Tg range of from about -50°C. to -105°C.
6. A process of Claim 1 wherein said alkenyl aro-matic monomer is styrene.
7. A process of Claim 1, said first reaction zone operating with essentially constant fillage of 10 to 90%
of its volume with said solution at a temperature of about 100 to 140°C. under a pressure of about 1 to 150 psig with isothermal and steady state polymerization.
of its volume with said solution at a temperature of about 100 to 140°C. under a pressure of about 1 to 150 psig with isothermal and steady state polymerization.
8. A process of Claim 1 wherein said second re-action zone is a staged, isobaric, stirred reaction zone, said partially polymerized solution being polymerized by progressive multistage substantially linear flow polymer-ization, all said stages operating with agitation and common evaporative vapor phase cooling under isobaric con-ditions, providing each said stage with steady state polymerization at a controlled temperature of about 130 to 180°C. and a pressure of about 7 to 28 psia.
9. A process of Claim 1 wherein said solution has present about 0.001 to 3.0% by weight of a free radical generating catalyst.
10. A process of Claim 9 wherein said free radical generating catalyst is selected from the group consisting of di-tert-butyl peroxide, tert-butyl peracetate, benzoyl per-oxide, lauroyl peroxide, tert-butyl perbenzoate, dicumyl peroxide, tert-butyl peroxide and isopropyl carbonate or mixtures thereof.
11. A process of Claim 1 wherein said solution com-prises a solution of a diene rubber in styrene.
12. A process of Claim 1 wherein said solution com-prises a solution of a diene rubber dissolved in styrene and acrylonitrile.
13. A process of Claim 12 wherein said styrene and acrylonitrile are present in amounts having a weight ratio of styrene to acrylonitrile of about 90:10 to 50:50.
14. A process of Claim 1 wherein said polymer is polystyrene.
15. A process of Claim 14 wherein said polystyrene has a weight average molecular weight of about 100,000 to 300,000.
16. A process of Claim 1 wherein said polymer is a styrene-acrylonitrile polymer having a weight ratio of styrene to acrylonitrile of about 90:10 to 50:50.
17. A process of Claim 16 wherein said styrene-acrylonitrile polymer has a weight average molecular weight of about 100,000 to 300,000.
18. A process of Claim 1 wherein said matrix phase comprises a matrix polymer selected from the group consist-ing of polystyrene and styrene-acrylonitrile polymer.
19. A process of Claim 1 wherein said diene block copolymer has the structure: polybutadiene-polystyrene, having a weight ratio of polybutadiene to polystyrene of 95:5 to 60:40.
20. A process of Claim 1 wherein said diene block copolymer has the structure: polystyrene-polybutadiene-poly-styrene, having a weight ratio of polybutadiene to polysty-rene of 95:5 to 60:40.
21. A process for the mass polymerization of mono-mer-rubber solutions comprising the steps:
A. continuously charging monomer having polybutadiene, butadiene-styrene block copolymer and polymer of said monomer dissolved therein to a first reaction zone operating at a steady-state polymerization conversion of about 20-45%, said monomer being styrene or a styrene-acrylonitrile mixture, said polymers being polysty-rene or styrene-acrylonitrile copoly-mers forming a first partially polymer-ized mixture, B. charging continuously said first mix-ture to a second polymerization zone operating at a steady-state polymeriza-tion conversion of about 50 to 85%
forming a second partially polymerized mixture, C. continuously separating residual mono-mers from said second mixture providing a polyblend with a matrix phase of said monomer having a dispersed mixed rubber phase of said polybutadiene and buta-diene-styrene block copolymer, said rub-ber phase being dispersed as rubber par-ticles having present about 1 to 5 parts of grafted and occluded polymers of said monomer per part of rubber.
A. continuously charging monomer having polybutadiene, butadiene-styrene block copolymer and polymer of said monomer dissolved therein to a first reaction zone operating at a steady-state polymerization conversion of about 20-45%, said monomer being styrene or a styrene-acrylonitrile mixture, said polymers being polysty-rene or styrene-acrylonitrile copoly-mers forming a first partially polymer-ized mixture, B. charging continuously said first mix-ture to a second polymerization zone operating at a steady-state polymeriza-tion conversion of about 50 to 85%
forming a second partially polymerized mixture, C. continuously separating residual mono-mers from said second mixture providing a polyblend with a matrix phase of said monomer having a dispersed mixed rubber phase of said polybutadiene and buta-diene-styrene block copolymer, said rub-ber phase being dispersed as rubber par-ticles having present about 1 to 5 parts of grafted and occluded polymers of said monomer per part of rubber.
22. A product of the process of Claim 21.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US150,274 | 1980-05-15 | ||
| US06/150,274 US4315083A (en) | 1980-05-15 | 1980-05-15 | Process for the continuous mass polymerization of polyblends |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1148687A true CA1148687A (en) | 1983-06-21 |
Family
ID=22533799
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000377592A Expired CA1148687A (en) | 1980-05-15 | 1981-05-14 | Process for the continuous mass polymerization of polyblends |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4315083A (en) |
| JP (1) | JPS5710614A (en) |
| AR (1) | AR223774A1 (en) |
| AU (1) | AU542704B2 (en) |
| BE (1) | BE888804A (en) |
| BR (1) | BR8102990A (en) |
| CA (1) | CA1148687A (en) |
| GB (1) | GB2076412B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3047303A1 (en) * | 1980-12-16 | 1982-07-29 | Basf Ag, 6700 Ludwigshafen | PROCESS FOR THE CONTINUOUS PRODUCTION OF RUBBER-MODIFIED POLYMERISATS OF VINYL FLAVORS, USE THEREOF FOR INJECTION MOLDING, AND MOLDED PARTS THEREOF |
| DE3047293A1 (en) * | 1980-12-16 | 1982-07-29 | Basf Ag, 6700 Ludwigshafen | METHOD FOR PRODUCING ABS POLYMERISATES, USE THEREOF, AND MOLDED PARTS THEREOF |
| US4524180A (en) * | 1982-05-21 | 1985-06-18 | The Dow Chemical Company | Rubber-modified, impact-resistant polymeric compositions |
| NL8304029A (en) * | 1983-11-23 | 1985-06-17 | Dow Chemical Nederland | RUBBER-REINFORCED POLYMERS OF MONOVINYLIDE AROMATIC COMPOUNDS HAVING A VERY GOOD RATIO BETWEEN GLOSS AND STRENGTH PROPERTIES AND A PROCESS FOR THEIR PREPARATION. |
| DE3409656A1 (en) * | 1984-03-16 | 1985-09-19 | Basf Ag, 6700 Ludwigshafen | METHOD FOR PRODUCING TRANSLUCENT POLYSTYRENE MODIFIED WITH RUBBER IMPACT-RESISTANT |
| JPH0649743B2 (en) * | 1986-05-30 | 1994-06-29 | 日本合成ゴム株式会社 | Method for manufacturing impact resistant resin |
| US4777210A (en) * | 1986-07-25 | 1988-10-11 | Cosden Technology, Inc. | Continuous production of high impact polystyrene |
| JPH0699617B2 (en) * | 1987-06-02 | 1994-12-07 | 出光石油化学株式会社 | Impact resistant styrene resin molding material and method for producing the same |
| MY111227A (en) * | 1993-06-29 | 1999-09-30 | Mitsui Chemicals Inc | Process for continuously preparing rubber modified styrene resins |
| US5414045A (en) * | 1993-12-10 | 1995-05-09 | General Electric Company | Grafting, phase-inversion and cross-linking controlled multi-stage bulk process for making ABS graft copolymers |
| JP2002275210A (en) * | 2000-10-24 | 2002-09-25 | Mitsui Chemicals Inc | Oil-resistant rubber-modified polystyrene composition |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1770392B2 (en) * | 1968-05-11 | 1980-07-03 | Basf Ag, 6700 Ludwigshafen | Process for the production of impact-resistant rubber-containing polymers |
| US3907939A (en) * | 1969-06-16 | 1975-09-23 | Ashland Oil Inc | Phosphite esters of hindered phenols |
| US3660535A (en) * | 1970-09-23 | 1972-05-02 | Dow Chemical Co | Process for the production of alkenyl aromatic polymers containing a reinforcing polymer therein |
| US3676527A (en) * | 1970-10-26 | 1972-07-11 | Shell Oil Co | Process for preparation of high impact polystyrene |
| US3903202A (en) * | 1973-09-19 | 1975-09-02 | Monsanto Co | Continuous mass polymerization process for polyblends |
| US4146589A (en) * | 1978-05-19 | 1979-03-27 | Monsanto Company | Method for preparing a monoalkenyl aromatic polyblend having a dispersed rubber phase as particles with a bimodal particle size distribution |
| US4252911A (en) * | 1979-10-17 | 1981-02-24 | Monsanto Company | Mass polymerization process for ABS polyblends |
-
1980
- 1980-05-15 US US06/150,274 patent/US4315083A/en not_active Expired - Lifetime
-
1981
- 1981-05-14 GB GB8114724A patent/GB2076412B/en not_active Expired
- 1981-05-14 AR AR285312A patent/AR223774A1/en active
- 1981-05-14 AU AU70569/81A patent/AU542704B2/en not_active Ceased
- 1981-05-14 JP JP7153481A patent/JPS5710614A/en active Pending
- 1981-05-14 BR BR8102990A patent/BR8102990A/en unknown
- 1981-05-14 CA CA000377592A patent/CA1148687A/en not_active Expired
- 1981-05-14 BE BE0/204788A patent/BE888804A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5710614A (en) | 1982-01-20 |
| GB2076412B (en) | 1984-11-21 |
| GB2076412A (en) | 1981-12-02 |
| AU542704B2 (en) | 1985-03-07 |
| AR223774A1 (en) | 1981-09-15 |
| BR8102990A (en) | 1982-02-02 |
| US4315083A (en) | 1982-02-09 |
| BE888804A (en) | 1981-11-16 |
| AU7056981A (en) | 1982-09-16 |
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